This invention relates in general to power take-off units and in particular to an improved structure for a bearing cap for use with a power take-off unit. This invention also relates to an improved structure for a pump mounting flange for use with a power take-off unit.
Power take-off units are well known mechanical devices which are commonly used on engine driven vehicles for rotatably driving one or more driven accessories, often for industrial and agricultural purposes. In general, a power take-off unit selectively provides a rotatable driving connection between the engine of the vehicle and the driven accessory. To accomplish this, a typical power take-off unit includes an input gear, an output shaft, and a gear set connected between the input gear and the output shaft. The input gear is adapted to be rotatably driven by the vehicle engine, while the output shaft is adapted to be connected to rotatably drive the driven accessory. The gear set provides one or more predetermined speed reduction gear ratios between the input gear and the output shaft. The gear set may also include a clutch for selectively disconnecting the output shaft from the input gear for intermittent operation of the driven accessory.
All of the above components of the power take-off unit are contained within a rigid housing. The input gear is rotatably supported within the housing such that a portion of the input gear extends outwardly through an opening formed through the housing. The housing of the power take-off unit is usually mounted about an opening formed through a case of a transmission of the vehicle. The outwardly extending portion of the input gear extends through the transmission case opening into meshing engagement with one of the transmission gears driven by the vehicle engine. As a result, the input gear of the power take-off unit is constantly rotatably driven by the transmission gear.
The input gear is usually supported for rotation on a non-rotatable idler shaft contained with the housing of the power take-off unit. The ends of the non-rotatable idler shaft are supported within respective openings formed through the housing of the power take-off unit. The ends of the rotatable output shaft, however, are rotatably supported in annular bearings mounted within the housing of the power take-off unit. To facilitate assembly and maintenance, the opposed sides of the housing of the power take-off unit are open, and respective bearing caps are provided for supporting the annular bearings and, therefore, the ends of the output shaft. The bearing caps have central openings formed therethrough which respectively support the annular roller bearings which, in turn, rotatably support the ends of the output shaft. The bearing caps are themselves secured to the housing of the power take-off unit by threaded fasteners which extend through peripheral apertures formed therethrough. In the past, four of such peripheral apertures were usually provided in the bearing cap to accommodate four threaded fasteners.
In many power take-off unit applications, the driven accessory is mounted directly on the housing of the power take-off unit. In those direct mount applications, a mounting surface for the driven accessory is provided on the exterior surface of one of the bearing caps, and a corresponding mounting flange is provided on the driven accessory. A plurality of peripheral apertures are formed through the mounting flange, through which respective threaded fasteners extend. The threaded fasteners secure the driven accessory to the bearing cap which, in turn, is secured to the housing of the power take-off unit.
In some instances, the mounting flange peripheral apertures correspond in number and location to the bearing cap peripheral apertures. In those instances, the four threaded fasteners mentioned above can extend not only through the four bearing cap peripheral apertures, but also through the four mounting flange peripheral apertures. Thus, the same four threaded fasteners can secure not only the bearing cap to the housing of the power take-off unit, but also the driven accessory to the bearing cap.
In other instances, however, the number and location of the mounting flange peripheral apertures are different from the bearing cap peripheral apertures. In those instances, the bearing cap must be formed having additional peripheral apertures to accommodate the threaded fasteners which secure the driven accessory to the bearing cap. As a result, a wide variety of bearings caps are necessary to accommodate a wide variety of mounting flanges. The lack of a single bearing cap structure which can accommodate a variety of mounting flange structures is undesirable for several readily apparent reasons. Thus, it would be desirable to provide an improved structure for a bearing cap for a power take-off unit which can accommodate a variety of mounting flange structures.
Separate and apart from the desirability of providing a single bearing cap structure which can accommodate a variety of mounting flange structures, it has also been found that existing bearing cap structures do not provide sufficient flexibility in adjusting the position of the driven accessory relative to the bearing cap and the power take-off unit. Inasmuch as the power take-off unit is secured to the transmission of the vehicle, it will be appreciated that the physical space available in that area of the vehicle is usually limited. It has been found that some driven accessories cannot be mounted on some vehicles because of a lack of clearance. Thus, it would also be desirable to provide an improved structure for a bearing cap for a power take-off unit which provides greater flexibility in adjusting the position of the driven accessory relative to the bearing cap and the power take-off unit.